ab1cf3df2d
Instead of a regular `Vec`. These vectors are usually very small, for example here is the histogram of sizes when running Sightglass's `pulldown-cmark` benchmark: ``` ;; Number of samples = 10332 ;; Min = 0 ;; Max = 11 ;; ;; Mean = 2.496128532713901 ;; Standard deviation = 2.2859559855427243 ;; Variance = 5.225594767838607 ;; ;; Each ∎ is a count of 62 ;; 0 .. 1 [ 3134 ]: ∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎ 1 .. 2 [ 2032 ]: ∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎ 2 .. 3 [ 159 ]: ∎∎ 3 .. 4 [ 838 ]: ∎∎∎∎∎∎∎∎∎∎∎∎∎ 4 .. 5 [ 970 ]: ∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎ 5 .. 6 [ 2566 ]: ∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎ 6 .. 7 [ 303 ]: ∎∎∎∎ 7 .. 8 [ 272 ]: ∎∎∎∎ 8 .. 9 [ 40 ]: 9 .. 10 [ 18 ]: ``` By using a `SmallVec` with capacity of 6 we avoid the vast majority of heap allocations and get some nice benchmark wins of up to ~1.11x faster compilation. <h3>Sightglass Benchmark Results</h3> ``` compilation :: nanoseconds :: benchmarks/spidermonkey/benchmark.wasm Δ = 340361395.90 ± 63384608.15 (confidence = 99%) main.so is 0.88x to 0.92x faster than smallvec.so! smallvec.so is 1.09x to 1.13x faster than main.so! [3101467423 3425524333.41 4060621653] main.so [2820915877 3085162937.51 3375167352] smallvec.so compilation :: cycles :: benchmarks/spidermonkey/benchmark.wasm Δ = 988446098.59 ± 184075718.89 (confidence = 99%) main.so is 0.88x to 0.92x faster than smallvec.so! smallvec.so is 1.09x to 1.13x faster than main.so! [9006994951 9948091070.66 11792481990] main.so [8192243090 8959644972.07 9801848982] smallvec.so compilation :: nanoseconds :: benchmarks/bz2/benchmark.wasm Δ = 7854567.87 ± 2215491.16 (confidence = 99%) main.so is 0.89x to 0.94x faster than smallvec.so! smallvec.so is 1.07x to 1.12x faster than main.so! [80354527 93864666.76 119789198] main.so [77554917 86010098.89 94726994] smallvec.so compilation :: cycles :: benchmarks/bz2/benchmark.wasm Δ = 22810509.85 ± 6434024.63 (confidence = 99%) main.so is 0.89x to 0.94x faster than smallvec.so! smallvec.so is 1.07x to 1.12x faster than main.so! [233358190 272593088.57 347880715] main.so [225227821 249782578.72 275097380] smallvec.so compilation :: nanoseconds :: benchmarks/pulldown-cmark/benchmark.wasm Δ = 10849521.41 ± 4324757.85 (confidence = 99%) main.so is 0.90x to 0.96x faster than smallvec.so! smallvec.so is 1.04x to 1.10x faster than main.so! [133875427 156859544.47 222455440] main.so [126073854 146010023.06 181611647] smallvec.so compilation :: cycles :: benchmarks/pulldown-cmark/benchmark.wasm Δ = 31508176.97 ± 12559561.91 (confidence = 99%) main.so is 0.90x to 0.96x faster than smallvec.so! smallvec.so is 1.04x to 1.10x faster than main.so! [388788638 455536988.31 646034523] main.so [366132033 424028811.34 527419755] smallvec.so ```
This crate contains the core Cranelift code generator. It translates code from an intermediate representation into executable machine code.